Transmission of pictures by electricity



Nov. 8, 1927.

" H. E. IVES TRANSMISSION OF PICTURES BY ELECTRIGITY 2 Sheets-Sheet 1Filed May 6, 1924 RVSA-D RPF RSF

Nov. 8, 1927.

H. E. IVES TRANSMISSION OF PICTURES BY ELECTRICITY Filed May 6, 1924 2Sheets-Sheet 2 Patented Nov. 8, 927.

, 5 UNITED STATES. PATENT oFF aEi HERBERT E. IVEsYoE MoNToLAIR, NEWJERSEY, ASSIGNOR To WESTERN E'LEcTRIcooMrA Y, INCORPORATED, or NEW YORK,N. Y., A CORPORATION or NEW YORK.

TRANSMISSION OF PICTURES BY ELECTRICITY.

Application filed May c.1924. Serial Nb. 711,333.

This invention relates to means for transmitting pictures by electricityand more particularly to an arrangement. for operating the scanningmechanism.

In systems heretofore known employin revolving drums for helicalscanning,'some mechanism has always been provided to return the drum toa given position after the transmission of each picture and beforestarting the transmission of another picture. Various devices have beenemployed. All have had their characteristic defects. Some were toocomplicated or delicate tobe practicable. Others required too muchoperat ing time. All were therefore expensive and uneconomical. 1

-An object of the present invention is to economize operating time insuch a system without sacrificing simplicity and reliability.

In one embodiment of the present invention, the equipment of a picturetransmission system employing transmitting and reproducing drums is soarranged that a picture maybe transmitted while the drums are moving ineitherdirection. The drums are driven by reversible La- Cour motors. Asthe drums rotate they also move axially with respect to the opticalportions of the system. The entire picture surface is thus traversedwhile the drums move axially" from one end to the other in eitherdirection. Each motor is coupled to its respective drum through afriction drive, the movement 'of the drum being controlled by amagnetically operated detentwhich prev vents rotation in eitherdirection. The motors are synchronized over one voice frequency carriercurrent channel while the picture characteristics are transmitted asmodulations of another voice frequency'carrier current channel ofdifierent frequency.

The novel features which areconsidcred characteristic of thisinventionare set forth with particularity in the appended claims. Theinvention, both as to its organization and method of operation togetherwith other olg'ects and advantages thereof,- will be further explainedin the following descri tion having reference to thev accompan ing rawins consisting of the following gures:

ig. 1 is a schematic circuit arrangement of the transmitting terminalequipment.

Fig. 2 is a schematic. circuit arrangement of the reproducing terminalequipment.

' Fig. 3 shows the mechanical arrangement of the magnetic detent.

Fig. 4 is a cross sectional view of the arrangement of Fig. 3. I

The general arrangement of the system is similar to that shown in acopending application of M. B. Long, Serial'No. 681,347,

filed December 18, 1923 and reference may be had thereto for a. moredetailed description of the system than is'gi'ven hereinafter. Thesame'referencecharacters are used in the several figures to designatethe same. elements;

The terminal equipments of Figs. 1 and 2 are each shownconnected to aline'L. The complete system is accordingly shown by connecting line L ofFig. 1 to line L of Fig. 2 through any circuit-suitable for transmittingordinary telephonecurrents such, forexample, as an ordinary telephoneline, a

carrier current telephone channel or a radio telephone channel.

Referring now to Fig. 1, a sending drum 5 is driven by a phonic wheel orLa Cour motor 6 by means of a shaft shown diagram matically by dottedlines. The coupling between drum 5 andthe, phonic wheel 6 is through afriction clutch 7. The phonic wheel 6 'isitse1f driven by tuning fork SFin. well known manner. An oscillator-amplifier SQ-A. supplies. carrierwaves to the line L through a circuit 8 and low-passjfilter SSF. Acontact9 on the tuning fork SF short-circuits circuit 8 periodically atthe frequencycf vibration ofithe tuning fork SF. At the reproducingterminal of Fig. 2,

these synchronizing waves are transmitted through low-pass filter "RSFto an amplifier-detector RSA-D, detected current from which drives thereproducing tuning fork RF by means of a driving magnet 10. The

receiving fork RF drives phonic wheel 11 in well known manner which inturn drlves reproducing drum 12 through friction clutch '13 and shaft14.. The shaft is shown diagrammatically by dotted lines.

At the transmitting ,terminal of Fig. l, th'e photo-electric cell 15'inside of sending drum is connected to the input circuit of picturecurrent amplifier PCA. Light from'a lamp.

17 is focused by means of lens 18 upon the parent. On the surface ofdrum 5, a trans- I surface of the sending drum 5 which is transparencyof the picture tube transmitted is secured and lightfrom thesource17-passing through this transparency of the picture into thephoto-electric cell 15 causes a varying cure rent to flow through thephoto-electric cell and to be impressedupon the input circuit of picturecurrent amplifier PCA. The output-circuit of the picture currenta'mpllfier .PCA is connected to the input circuit of the .modulator PM.An oscillator PO supplies the carrier waves for the transmission of thepicture characteristics. These waves are amplified in an amplifierMCAand; then transmitted to the line L through a high-pass Waves from theoscillator PO maybe impressed upon the amplifier MCA by either one oftwo paths. One path extends from the 27, and potentiometer 28 toamplifier MCAQ The energizing circuit for the upper winding of relay 27includes battery 46, switch 47 and relay 48. If this energizing circuitis opened at switch 47, the lower winding of relay 27 is efiective toclose contact 26. When switch 47 is closed (as shown) the upper windingof relay 27 is efiective to'close eontact 29. Under this same condition,armature 49 of relay 48 is attracted and locks the sending drum 5against rotation in either direction.

At the reproducing terminal of-Fig. 2, picture carrier waves from theoscillator P0 are transmitted by high-pass filter RPF, amplified byamplifier EPA and impressed upon reproducing demodulatorfRPD. Connectedin the output circuit of demodulator" RPD is a battery 30, movable strin-31 of light valve. V and winding 32 of re ay 33. 'Themovement of thestring 31 of light valve V controls the amount of light from lamp 43which may affect a sensitive light recording blank or film secured tothe reproducing drum 12. The light from the lamp 43 is directed firstupon the movable spring A, 31 of light valve V. An image of the openingformed by the string 31 is then focused contact 35 by battery 37.

upon the surface of the drum by the lens as shown. I

The armature of relay 33 is held in the position shown with contact34closed by thecurrent flowing in-the winding 32 when carrler -waves areimpressed upon the input circuit of demodulator RPD. When such waves arenot being received, the armature.

of relay 33 is moved into a position closing current 1n winding 36 from:The closure of switch 38 completes a circuit for relay 39 throughbattery 40 The c urrent in relay 39 attracts its aianature 41 to lockdrum 12 and prevent its rotation in either direction. Another circuitfor relay 39 through battery 40 is closed when contact 34 of relay 33 isclosed even though the switch 38 is opened. It is to be noted that theclosure of switch 38 forms a' short circuit about the contact 34. Acircuit which is completed by the closure of which 42 and contact 35,forms a short-circuit about the winding 32 of relay 33.

The well known three-electrode electron discharge devices are preferablyused throughout the system for the oscillators, modulators, demodulatorsand amplifiers. The filtersare'designed according to the principles setforth in Campbell Patent No. 1,227,113, May 22, 1917.

The detent mechanism will now ,be described with reference to Figs. 3and 4. The same mechanism may be used at both the transmitting andreproducing terminals. It

will therefore be described by using only the reference characters 'ofthe transmitting terminal of Fig. l. The magnet 39, armature 41 and drum12 of .Fig. 2 correspond respectively, to the magnet 48, armature 49 anddrum 5 of Fig. 1.

The drum 5- and the detent mechanism in- I eluding magnet 48 andarmature 49 are mounted on a carriage 50 which may slide back and forthalong guides 51 mounted on a frame 52. The threaded shaft 53 is. gearedto shaft 54 so that their speeds of rotation bear a definite relation toeach other. Preferably, this speed ratio is unity. The threaded shaft 53engageswith screw collar 55 attached to the frame 50 so that therotation of shaft 53 causes the movement of frame 50 along the guides51. Mounted on the shaft 54in fixed relation thereto is a collar 56which has a square notch 57 cut in its periphery. The notch 57 is justlarge enough to receive one end of the armature 49 which drops into thenotch when the magnet 48 is energized .and so prevents rotation'of thedrum 5 in either direction. When drum 5 is held stationary, shaft 53 isprevented from rotating and movement of the frame 50 with respect to theguides 51 is prevented. The armatu1'e'49 is normally held out ofengagement with the collar 56 by a spring 58.

Method of operation.

The method of operation willnow be de-" scribed.

Drums 5 and 12 are set at one end or the other of their axial travel. Atransparency of the picture is placed on drum 5 and a sensitive recordblank is secured to drum 12. Switch 47 is closed which locks drum '5through the energization oft relay 48 and closes contact 29 of relay 27.Switch 38 is closed which locks drum 12 by the ehergization of relay 39.Switch is kept open.-

The transmission apparatus, such as the oscillators, amplifiers, etc,are then energized. Synchronizing carrier waves from theoscillator-amplifier SO-A are transmitted lator RPD. Demodulated currentflows in string 31 of light valve V and winding 32 of relay 33 to closecontact 34. v Tuning fork SF is then set in vibratio and phonic wheel 6is started in such a direction as to tend to move drum 5 toward itsopposite end. The rotation of phonic wheel 6 tends to rotate sendingdrum 5 through fric tion clutch 7 but drum 5 is locked by armature 49 ofrelay 48. At contact 9 of fork contact 35 places a short-circuit aroundwinding 32, so that the subsequent receipt of carrier current bydemodulator RPD, upon the closure of contact 26, cannot again energizewinding 32 to lock drum 12.

The varying tone values of the transparency of the picturecause varyingcurrents through the photo-electric cell 15. Carrier waves fromoscillator P0 are modulated by these varying currents afteramplification in amplifier and PCS andtransmitted to demodulator RPD.Corresponding varying currents in the output circuit of demodulatorRPDcauses. movement of the string 31 of ,light valve V so that the imageof the aperture formed by string. 31 on the light record blank on drum12 varies in accordance with the light'transmitted through the SF, thetrain of carrier waves from oscillator-amplifier SO -A .is periodicallyinterrupted at circuit 8, so that trains, of waves are transmitted tothe line L. These waves in amplifier-detector RSA-D cause impulses ofcurrent in driving magnet 10 to drive tuning fork RF in synchronism withtuning fork SF. Phonic wheel 11 is started in a transparency of thepicture ,at the sending drum 5. g I

Atthe conclusion of the process, switch 47 is closed to locktransmitting drum 5. The

attendant at the reproducing station, observing that the movement of thelight valve has direction tending to move cylinder 12 to its oppositeend. The rotation of phonic wheel 11 tends to drive drum 12 throughfriction clutch 13 but is prevented from doing so by armature 41 ofrelay 39.

Switch .23 is now closed and switch 38.is

opened. Picture carrier; waves fromoscilla tor P0 are impressed upon theinput circuit of modulator PM, the output circuit of which is open,however, at contact 26 of relay 27. Drum 12 is held in locked positionby the energization of relay 39 through a circuit including contact 34.Everything is now in readiness to start the transmission of the picture.Phonic wheels 6 and 11 are rotating synchronously. Drums 5 and 12 arelockedagainst rotation. Light-valve V is energized by demodulatedpicture car rier waves.

To start the actual transmission, switch 47 is opened and left openduring the transmissionprocess. The opening of switch 47 deenergizesrelay 48 which unlocks sending drum 5. The. upper windingpf relay 2? issimultaneously deenergized so that contact 26 is closed and the outputcircuit 25 of modulator PM is connected to. the inputcircuit ofamplifier MCA.

During the time that the armatureof re lay 27 is moving from contact 29to contact 26, the picture carrier waves are. interrupted.

ceased, can either open switch 42 or close switch 38 o both to lock thereproducing drum 12.

The direction of rotation of phonic wheels- 6 and 11 is now reversed.Another light sensitive record blank is placed on drum 12. If adifferent picture is to be transmitted, a transparency of such pictureis placed on sending drum 5. The same transparency is of course used ifit is desired to transmit the same picture. If switch 42 only had beenpreviously opened to lock reproducing drum 12, it may now be closed andthe system is in readiness to transmit another picture. If switch 38 hadalso been closed, it must be opened before the transmitting process canbegin. The process of transmitting this second picture is the sameasthat of the first except that the axial movement of the drums 5 and 12is in an opposite direction.

When transmitting pictures, according to the present invention, no. timeis lost between pictures in returning the sending andreproducing drumsto starting positions. By the arrangement of this invention, the sendingand reproducing drums at the finish 'ofone'picture are in position forthe start- Such interruption allows the armature of reing of another. Nocomplicated apparatus is required and a large saving in operating timeis effected.

Various modifications of the specific embodiment of the invention whichhas been described may be made without departing from the scope of theinvention as defined in the appended claims.

What is claimed is:

' 1. In a system for the transmission of picturesbyelectricity, opticalmeans to scan successive elemental areas of a picture sur-- face in apredetermined sequence for the transmission of a picture and to scan theall I and means to rotate it in either oftwo; di-

disable said prevention means.

motions and simultaneously move it axially with respect to thescanningmeans.

2. In a system forthe transmission of pictures by electricity, a picturedrum, means to illuminate a small area of the surface of said drum,means to rotate said drum in either of two directions and simultaneouslymove it axially with respect to 'said illuminating means, mean s toprevent motion of said drum in either direction, and means to 31 In asystem for the transmission of pictures by electricity, a picture .drum,an optical arrangement to illuminate a small area of the surface of saiddrum, a friction drive for rotating said drum and moving it axially ineither'of two directions with respect to saidoptical arrangement, a'detent to prevent rotation of said drum in either direction, andJelectromagnetic means for releasing said detent.

ls-In a system for the transmission of pictures by electricity, sendingand reproducing picture drums, means torotate said drums synchronouslyand to move them' axially in either direction, means to prevent rotationof said drums, and meansto start them synchronously in either direction.v 5. In a system for transmitting pictures i'he pictures to besuccessively transmitted, means including a rotatableelement for reroducing the picture,.andmeans controlled y carrier waves from saidsource to control the rotation of said element in'either 40- direction.I .7 4

6; In a system. for the transmission of pictures by electricity, acircuit over which carrierwvaves are received, arep'roducing drum, alight valve, an electron'discha-rge in response to the receipt ofcarrier waves, means to unlock said-drum due to an interruption inreceipt of said carrier waves and means to prevent a subsequent lockingof said reproducing drum when carrier waves are again received.-

7. In an electrical system, a movable device capable of moving in eitherone oftwo directions, means to cause movement'of said device, a sourceof carrier waves, ,and meansv 7. under the eontrolof carrier'waves' fromsaid source to effect the movement of said movable device in eitherdirection.

In witness whereof, I hereunto subscribe my name this 29th day of AprilA. .D. 1924.

-HERBERT E. iv'ns.

45 demodulator, means to locksaid reproducing vdrum againstmotion'ineither direction

